Tubular expansion apparatus and method

Abstract

Tools for expanding downhole tubulars into each other or in open hole are disclosed. One embodiment uses a movable cone biased by Bellville washers to move longitudinally against such bias and allow collets to move radially in or out to a predetermined maximum diameter. A release system allows collet retraction to avoid hang up on removal. In an alternate embodiment, more suitable for open hole applications, pressurized gas pushes a movable cone longitudinally against the collets. A stationary cone is on the opposite side of the collets from the movable cone. The collet rides out or in between the cones and raises the gas pressure when forced in. A pressure actuated release allows the lower cone to shift downwardly to allow the collets to retract for removal.

Description

PRIORITY INFORMATION[0001]This application claims the benefit of U.S. Provisional Application No. 60 / 326,364 on Oct. 1, 2001.FIELD OF THE INVENTION[0002]The field of this invention relates to expansion of tubulars into other tubulars downhole or in open hole using liners, screens or tubing, both as a method and the specific equipment, which can be used to accomplish the method.BACKGROUND OF THE INVENTION[0003]In the past, tubulars have been expanded into casing for the purposes of patching broken casing or to hang a liner string. The casing, in different applications can have different wall thickness for a specific casing size, depending on the particular well requirements. Because of this, there is a problem with using a cone that is driven into a tubular to expand it into a given casing size. If the wedge or cone is a fixed dimension, it can hang up in heavy wall casing, where the need to expand the tubular is less than if the casing had a thinner wall.[0004]In open hole the same ...

AI Technical Summary

Benefits of technology

The patent describes tools used to expand downhole tubulars in each other or in open hole. One tool uses a movable cone to push collets out to a predetermined maximum diameter, while a release system allows for collet retraction to prevent hang up on removal. Another tool uses pressurized gas to push the movable cone against the collets, which raises the gas pressure when forced in. A pressure actuated release allows for the collets to retract for removal. These tools help to expand downhole tubulars and improve the process of drilling and wellbore construction.

Problems solved by technology

Because of this, there is a problem with using a cone that is driven into a tubular to expand it into a given casing size.

In open hole the same problem can arise, as well as other problems.

An open hole borehole however usually is not consistent in diameter and shape, and may consist of washed out areas as well as sections that may have partially collapsed inward.

This makes the use of a fixed-diameter swedge cone somewhat impractical for open hole applications, as it does not have the capacity to adjust with irregularities in the borehole.

A fixed-diameter swedge cannot compensate for enlarged holes to provide the borehole wall-to-liner contact, and may prohibit passage through the liner / screen when encountering a collapsed area in the borehole.

This can create potential hang up problems on the removal operation after expansion.

This design makes it difficult to adjust the preload on the Bellville washers.

Mechanical drive mechanisms, while perhaps simpler, are impractical due to the relatively large axial displacement of the upper drive cone during normal operations of the device (i.e. a Belleville spring stack would be impractically long to allow for such high axial movement at the desired force for liner / screen expansion).

A coiled spring would simply be too big in diameter for the available space and the force delivery requirement.

Also, this same process occurs if a collapsed section of the borehole is encountered.

Images